General question about programming languages...

[Sink0]

I could not find any better topic to ask this. This question is generic and not only related to C programming. If it is not suited to this forum please feel free to remove it.

My question is related to which programming language compilers are programmed. I mean, Is a GCC programmed in assembly? Or ForTram? How about C++ compilers, are they programmed in C, or a lower level programming language. Usually a high level programming language as Java, C# is programmed in C++? Is there any common sense about this, or is it completely random?

Let me know if i was kind confusing.

[CommonTater]

Well, yes it is confusing....

When working with Pascal one of the tests of the compiler was to make it compile a copy of itself... That is, most Pascal compilers were written in previous versions of Pascal. I believe the first one was written in C.

C compilers (and not a few others) are usually written in mixtures of C and ASM.

C++ was originally programmed in C but now it's largely like Pascal, written in C++

So... no there's no real logic to it. You can write a compiler in any language that compiles to machine code.

[Sink0]

Wow, i would never expect that a compiler it is writen on a previous version of its own language. .. very weird. .... well thank you about the answer!

Any other comments are still accepted!!

Thank you!

[cas]

Is there any common sense about this, or is it completely random?

A compiler developer is going to write in whatever language he prefers for the task; often, this is the target language, which makes some sort of sense. If you're writing a compiler for a language, you're probably comfortable with that language.

There will probably be some limitations. Ruby (which is not a compiled language) is written in C, presumably in part for speed—although large parts of its standard library are in Ruby. There's also the problem of bootstrapping: how can you build a compiler for the first time? Generally it's not hard: you use another language, and from that point on, you can write a compiler in its own language (so we've had C-based C compilers for decades). But for end-users it's another matter. Most development systems will have C, so often a language will provide a stripped-down C version of its compiler. This compiler is built and used to build a full-featured compiler in its own language.

Compilers aren't always implemented in terms of themselves, though: Clang, the LLVM-base C compiler, is written in C++. That works best for the developers, so it's what they chose.

The common sense is, use what you know. It's not random, but choices based on a developer's preferences combined with the reality of what various languages are able to do.

[Epy]

This is something that confused me when I was learning--how can a compiler for a certain language be written in that language? You have to realize that all it's doing is analyzing text and converting it to machine instructions, which it dumps to a file. If you want to oversimplify it, it's just table lookups.

Ruby (which is not a compiled language) is written in C, presumably in part for speed

Just had to comment, that's too funny to say considering that Ruby is one of the slowest languages available currently. I think BASIC is faster than Ruby.

[Sebastiani]

I could not find any better topic to ask this. This question is generic and not only related to C programming. If it is not suited to this forum please feel free to remove it.

My question is related to which programming language compilers are programmed. I mean, Is a GCC programmed in assembly? Or ForTram? How about C++ compilers, are they programmed in C, or a lower level programming language. Usually a high level programming language as Java, C# is programmed in C++? Is there any common sense about this, or is it completely random?

Let me know if i was kind confusing.

The very first C compiler was written in assembly. Rewritten in C, it was then, well...recompiled. It's a sort of "boot-strapping" kind of thing, really; once you are able to write the compiler in the language itself, whole new possibilities open up; you can use all of the fancy data structures and methods to reimplement any aspect of the compiler that you wish. Pretty useful technique, actually.

[cpjust]

A better question would be: what was the very first compiler written in? A needle & a magnet?

[GReaper]

A better question would be: what was the very first compiler written in? A needle & a magnet?

In was built by using pure assembly.

But i have an even better one:
How was the first assembler built? ( I can't imagine people programming in machine code! )

[fronty]

C compilers (and not a few others) are usually written in mixtures of C and ASM..

I would drop the assembly part out of that.

How was the first assembler built? ( I can't imagine people programming in machine code! )

First people programmed in machine code, then came hand assembling and finally assemblers.

And in fact first C++ compiler was written in C++.

[GReaper]

And in fact first C++ compiler was written in C++.

How was that possible?!

[laserlight]

How was that possible?!

Read Stroustrup's answer to the question Which language did you use to write C++?

[GReaper]

Well, how about that?! You never know enough!...

[nonoob]

The question becomes how does one program in machine code on today's PCs which don't have any front panel of toggle switches to enter in binary op codes and registers? It can't be done any more.

I guess at some point someone has to transfer a ROM chip with boot code to a new machine and give it at least some smarts that way. Smarts enough to be able to respond to keyboard, some ports, etc. Disk drives already come with controllers that are micro processors themselves and have firmware programs in them.

I came from the good ol' days where mini computers had lights and switches on their front panels. The thing can be shipped totally empty. You put in a rudimentary loader into 64 words of memory. That's enough to read a paper tape through the teletype machine. The paper tape contained the BASIC interpreter and minimal I/O drivers for card reader, printer, cassette tape storage system.

[cyberfish]

You can still build one yourself. I know a prof of mine has been building a computer on a breadboard using discrete transistors.

[zacs7]

So... no there's no real logic to it. You can write a compiler in any language that compiles to machine code.

More specifically, you can write a compiler in any language. It doesn't have to compile to machine code...